Stephen W. Hawking, a world-renowned physicist, died at age 76 at his house in Cambridge, England.

According to The Washington Post, Hawking’s family pronounced the death without further details.

Hawking was known for is work with black hole and relativity. He was diagnosed with a rare form of motor neuron disease. He was paralyzed ever since and could only speak with a computer-synthesized voice.

“My goal is simple,” Hawking once said, according to The Washington Post. “It is complete understanding of the universe, why it is as it is and why it exists at all.”